This is grep.info-t, produced by makeinfo version 6.0 from grep.texi. This manual is for ‘grep’, a pattern matching engine. Copyright © 1999-2002, 2005, 2008-2016 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”. INFO-DIR-SECTION Text creation and manipulation START-INFO-DIR-ENTRY * grep: (grep). Print lines matching a pattern. END-INFO-DIR-ENTRY  File: grep.info-t, Node: Top, Next: Introduction, Up: (dir) grep **** ‘grep’ prints lines that contain a match for a pattern. This manual is for version 2.25 of GNU Grep. This manual is for ‘grep’, a pattern matching engine. Copyright © 1999-2002, 2005, 2008-2016 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”. * Menu: * Introduction:: Introduction. * Invoking:: Command-line options, environment, exit status. * Regular Expressions:: Regular Expressions. * Usage:: Examples. * Reporting Bugs:: Reporting Bugs. * Copying:: License terms for this manual. * Index:: Combined index.  File: grep.info-t, Node: Introduction, Next: Invoking, Prev: Top, Up: Top 1 Introduction ************** ‘grep’ searches input files for lines containing a match to a given pattern list. When it finds a match in a line, it copies the line to standard output (by default), or produces whatever other sort of output you have requested with options. Though ‘grep’ expects to do the matching on text, it has no limits on input line length other than available memory, and it can match arbitrary characters within a line. If the final byte of an input file is not a newline, ‘grep’ silently supplies one. Since newline is also a separator for the list of patterns, there is no way to match newline characters in a text.  File: grep.info-t, Node: Invoking, Next: Regular Expressions, Prev: Introduction, Up: Top 2 Invoking ‘grep’ ***************** The general synopsis of the ‘grep’ command line is grep OPTIONS PATTERN INPUT_FILE_NAMES There can be zero or more OPTIONS. PATTERN will only be seen as such (and not as an INPUT_FILE_NAME) if it wasn’t already specified within OPTIONS (by using the ‘-e PATTERN’ or ‘-f FILE’ options). There can be zero or more INPUT_FILE_NAMES. * Menu: * Command-line Options:: Short and long names, grouped by category. * Environment Variables:: POSIX, GNU generic, and GNU grep specific. * Exit Status:: Exit status returned by ‘grep’. * grep Programs:: ‘grep’ programs.  File: grep.info-t, Node: Command-line Options, Next: Environment Variables, Up: Invoking 2.1 Command-line Options ======================== ‘grep’ comes with a rich set of options: some from POSIX and some being GNU extensions. Long option names are always a GNU extension, even for options that are from POSIX specifications. Options that are specified by POSIX, under their short names, are explicitly marked as such to facilitate POSIX-portable programming. A few option names are provided for compatibility with older or more exotic implementations. * Menu: * Generic Program Information:: * Matching Control:: * General Output Control:: * Output Line Prefix Control:: * Context Line Control:: * File and Directory Selection:: * Other Options:: Several additional options control which variant of the ‘grep’ matching engine is used. *Note grep Programs::.  File: grep.info-t, Node: Generic Program Information, Next: Matching Control, Up: Command-line Options 2.1.1 Generic Program Information --------------------------------- ‘--help’ Print a usage message briefly summarizing the command-line options and the bug-reporting address, then exit. ‘-V’ ‘--version’ Print the version number of ‘grep’ to the standard output stream. This version number should be included in all bug reports.  File: grep.info-t, Node: Matching Control, Next: General Output Control, Prev: Generic Program Information, Up: Command-line Options 2.1.2 Matching Control ---------------------- ‘-e PATTERN’ ‘--regexp=PATTERN’ Use PATTERN as the pattern. If this option is used multiple times or is combined with the ‘-f’ (‘--file’) option, search for all patterns given. (‘-e’ is specified by POSIX.) ‘-f FILE’ ‘--file=FILE’ Obtain patterns from FILE, one per line. If this option is used multiple times or is combined with the ‘-e’ (‘--regexp’) option, search for all patterns given. The empty file contains zero patterns, and therefore matches nothing. (‘-f’ is specified by POSIX.) ‘-i’ ‘-y’ ‘--ignore-case’ Ignore case distinctions, so that characters that differ only in case match each other. Although this is straightforward when letters differ in case only via lowercase-uppercase pairs, the behavior is unspecified in other situations. For example, uppercase “S” has an unusual lowercase counterpart “ſ” (Unicode character U+017F, LATIN SMALL LETTER LONG S) in many locales, and it is unspecified whether this unusual character matches “S” or “s” even though uppercasing it yields “S”. Another example: the lowercase German letter “ß” (U+00DF, LATIN SMALL LETTER SHARP S) is normally capitalized as the two-character string “SS” but it does not match “SS”, and it might not match the uppercase letter “ẞ” (U+1E9E, LATIN CAPITAL LETTER SHARP S) even though lowercasing the latter yields the former. ‘-y’ is an obsolete synonym that is provided for compatibility. (‘-i’ is specified by POSIX.) ‘-v’ ‘--invert-match’ Invert the sense of matching, to select non-matching lines. (‘-v’ is specified by POSIX.) ‘-w’ ‘--word-regexp’ Select only those lines containing matches that form whole words. The test is that the matching substring must either be at the beginning of the line, or preceded by a non-word constituent character. Similarly, it must be either at the end of the line or followed by a non-word constituent character. Word-constituent characters are letters, digits, and the underscore. This option has no effect if ‘-x’ is also specified. ‘-x’ ‘--line-regexp’ Select only those matches that exactly match the whole line. For a regular expression pattern, this is like parenthesizing the pattern and then surrounding it with ‘^’ and ‘$’. (‘-x’ is specified by POSIX.)  File: grep.info-t, Node: General Output Control, Next: Output Line Prefix Control, Prev: Matching Control, Up: Command-line Options 2.1.3 General Output Control ---------------------------- ‘-c’ ‘--count’ Suppress normal output; instead print a count of matching lines for each input file. With the ‘-v’ (‘--invert-match’) option, count non-matching lines. (‘-c’ is specified by POSIX.) ‘--color[=WHEN]’ ‘--colour[=WHEN]’ Surround the matched (non-empty) strings, matching lines, context lines, file names, line numbers, byte offsets, and separators (for fields and groups of context lines) with escape sequences to display them in color on the terminal. The colors are defined by the environment variable ‘GREP_COLORS’ and default to ‘ms=01;31:mc=01;31:sl=:cx=:fn=35:ln=32:bn=32:se=36’ for bold red matched text, magenta file names, green line numbers, green byte offsets, cyan separators, and default terminal colors otherwise. The deprecated environment variable ‘GREP_COLOR’ is still supported, but its setting does not have priority; it defaults to ‘01;31’ (bold red) which only covers the color for matched text. WHEN is ‘never’, ‘always’, or ‘auto’. ‘-L’ ‘--files-without-match’ Suppress normal output; instead print the name of each input file from which no output would normally have been printed. The scanning of each file stops on the first match. ‘-l’ ‘--files-with-matches’ Suppress normal output; instead print the name of each input file from which output would normally have been printed. The scanning of each file stops on the first match. (‘-l’ is specified by POSIX.) ‘-m NUM’ ‘--max-count=NUM’ Stop reading a file after NUM matching lines. If the input is standard input from a regular file, and NUM matching lines are output, ‘grep’ ensures that the standard input is positioned just after the last matching line before exiting, regardless of the presence of trailing context lines. This enables a calling process to resume a search. For example, the following shell script makes use of it: while grep -m 1 PATTERN do echo xxxx done < FILE But the following probably will not work because a pipe is not a regular file: # This probably will not work. cat FILE | while grep -m 1 PATTERN do echo xxxx done When ‘grep’ stops after NUM matching lines, it outputs any trailing context lines. Since context does not include matching lines, ‘grep’ will stop when it encounters another matching line. When the ‘-c’ or ‘--count’ option is also used, ‘grep’ does not output a count greater than NUM. When the ‘-v’ or ‘--invert-match’ option is also used, ‘grep’ stops after outputting NUM non-matching lines. ‘-o’ ‘--only-matching’ Print only the matched (non-empty) parts of matching lines, with each such part on a separate output line. ‘-q’ ‘--quiet’ ‘--silent’ Quiet; do not write anything to standard output. Exit immediately with zero status if any match is found, even if an error was detected. Also see the ‘-s’ or ‘--no-messages’ option. (‘-q’ is specified by POSIX.) ‘-s’ ‘--no-messages’ Suppress error messages about nonexistent or unreadable files. Portability note: unlike GNU ‘grep’, 7th Edition Unix ‘grep’ did not conform to POSIX, because it lacked ‘-q’ and its ‘-s’ option behaved like GNU ‘grep’’s ‘-q’ option.(1) USG-style ‘grep’ also lacked ‘-q’ but its ‘-s’ option behaved like GNU ‘grep’’s. Portable shell scripts should avoid both ‘-q’ and ‘-s’ and should redirect standard and error output to ‘/dev/null’ instead. (‘-s’ is specified by POSIX.) ---------- Footnotes ---------- (1) Of course, 7th Edition Unix predated POSIX by several years!  File: grep.info-t, Node: Output Line Prefix Control, Next: Context Line Control, Prev: General Output Control, Up: Command-line Options 2.1.4 Output Line Prefix Control -------------------------------- When several prefix fields are to be output, the order is always file name, line number, and byte offset, regardless of the order in which these options were specified. ‘-b’ ‘--byte-offset’ Print the 0-based byte offset within the input file before each line of output. If ‘-o’ (‘--only-matching’) is specified, print the offset of the matching part itself. When ‘grep’ runs on MS-DOS or MS-Windows, the printed byte offsets depend on whether the ‘-u’ (‘--unix-byte-offsets’) option is used; see below. ‘-H’ ‘--with-filename’ Print the file name for each match. This is the default when there is more than one file to search. ‘-h’ ‘--no-filename’ Suppress the prefixing of file names on output. This is the default when there is only one file (or only standard input) to search. ‘--label=LABEL’ Display input actually coming from standard input as input coming from file LABEL. This is especially useful when implementing tools like ‘zgrep’; e.g.: gzip -cd foo.gz | grep --label=foo -H something ‘-n’ ‘--line-number’ Prefix each line of output with the 1-based line number within its input file. (‘-n’ is specified by POSIX.) ‘-T’ ‘--initial-tab’ Make sure that the first character of actual line content lies on a tab stop, so that the alignment of tabs looks normal. This is useful with options that prefix their output to the actual content: ‘-H’, ‘-n’, and ‘-b’. In order to improve the probability that lines from a single file will all start at the same column, this also causes the line number and byte offset (if present) to be printed in a minimum-size field width. ‘-u’ ‘--unix-byte-offsets’ Report Unix-style byte offsets. This option causes ‘grep’ to report byte offsets as if the file were a Unix-style text file, i.e., the byte offsets ignore carriage returns that were stripped. This will produce results identical to running ‘grep’ on a Unix machine. This option has no effect unless the ‘-b’ option is also used; it has no effect on platforms other than MS-DOS and MS-Windows. ‘-Z’ ‘--null’ Output a zero byte (the ASCII NUL character) instead of the character that normally follows a file name. For example, ‘grep -lZ’ outputs a zero byte after each file name instead of the usual newline. This option makes the output unambiguous, even in the presence of file names containing unusual characters like newlines. This option can be used with commands like ‘find -print0’, ‘perl -0’, ‘sort -z’, and ‘xargs -0’ to process arbitrary file names, even those that contain newline characters.  File: grep.info-t, Node: Context Line Control, Next: File and Directory Selection, Prev: Output Line Prefix Control, Up: Command-line Options 2.1.5 Context Line Control -------------------------- Regardless of how these options are set, ‘grep’ will never print any given line more than once. If the ‘-o’ (‘--only-matching’) option is specified, these options have no effect and a warning is given upon their use. ‘-A NUM’ ‘--after-context=NUM’ Print NUM lines of trailing context after matching lines. ‘-B NUM’ ‘--before-context=NUM’ Print NUM lines of leading context before matching lines. ‘-C NUM’ ‘-NUM’ ‘--context=NUM’ Print NUM lines of leading and trailing output context. ‘--group-separator=STRING’ When ‘-A’, ‘-B’ or ‘-C’ are in use, print STRING instead of ‘--’ between groups of lines. ‘--no-group-separator’ When ‘-A’, ‘-B’ or ‘-C’ are in use, do not print a separator between groups of lines. Here are some points about how ‘grep’ chooses the separator to print between prefix fields and line content: • Matching lines normally use ‘:’ as a separator between prefix fields and actual line content. • Context (i.e., non-matching) lines use ‘-’ instead. • When context is not specified, matching lines are simply output one right after another. • When context is specified, lines that are adjacent in the input form a group and are output one right after another, while by default a separator appears between non-adjacent groups. • The default separator is a ‘--’ line; its presence and appearance can be changed with the options above. • Each group may contain several matching lines when they are close enough to each other that two adjacent groups connect and can merge into a single contiguous one.  File: grep.info-t, Node: File and Directory Selection, Next: Other Options, Prev: Context Line Control, Up: Command-line Options 2.1.6 File and Directory Selection ---------------------------------- ‘-a’ ‘--text’ Process a binary file as if it were text; this is equivalent to the ‘--binary-files=text’ option. ‘--binary-files=TYPE’ If a file’s data or metadata indicate that the file contains binary data, assume that the file is of type TYPE. Non-text bytes indicate binary data; these are either output bytes that are improperly encoded for the current locale (*note Environment Variables::), or null input bytes when the ‘-z’ (‘--null-data’) option is not given (*note Other Options::). By default, TYPE is ‘binary’, and when ‘grep’ discovers that a file is binary it suppresses any further output, and instead outputs either a one-line message saying that a binary file matches, or no message if there is no match. If TYPE is ‘without-match’, when ‘grep’ discovers that a file is binary it assumes that the rest of the file does not match; this is equivalent to the ‘-I’ option. If TYPE is ‘text’, ‘grep’ processes a binary file as if it were text; this is equivalent to the ‘-a’ option. When TYPE is ‘binary’, ‘grep’ may treat non-text bytes as line terminators even without the ‘-z’ (‘--null-data’) option. This means choosing ‘binary’ versus ‘text’ can affect whether a pattern matches a file. For example, when TYPE is ‘binary’ the pattern ‘q$’ might match ‘q’ immediately followed by a null byte, even though this is not matched when TYPE is ‘text’. Conversely, when TYPE is ‘binary’ the pattern ‘.’ (period) might not match a null byte. _Warning:_ The ‘-a’ (‘--binary-files=text’) option might output binary garbage, which can have nasty side effects if the output is a terminal and if the terminal driver interprets some of it as commands. On the other hand, when reading files whose text encodings are unknown, it can be helpful to use ‘-a’ or to set ‘LC_ALL='C'’ in the environment, in order to find more matches even if the matches are unsafe for direct display. ‘-D ACTION’ ‘--devices=ACTION’ If an input file is a device, FIFO, or socket, use ACTION to process it. If ACTION is ‘read’, all devices are read just as if they were ordinary files. If ACTION is ‘skip’, devices, FIFOs, and sockets are silently skipped. By default, devices are read if they are on the command line or if the ‘-R’ (‘--dereference-recursive’) option is used, and are skipped if they are encountered recursively and the ‘-r’ (‘--recursive’) option is used. This option has no effect on a file that is read via standard input. ‘-d ACTION’ ‘--directories=ACTION’ If an input file is a directory, use ACTION to process it. By default, ACTION is ‘read’, which means that directories are read just as if they were ordinary files (some operating systems and file systems disallow this, and will cause ‘grep’ to print error messages for every directory or silently skip them). If ACTION is ‘skip’, directories are silently skipped. If ACTION is ‘recurse’, ‘grep’ reads all files under each directory, recursively, following command-line symbolic links and skipping other symlinks; this is equivalent to the ‘-r’ option. ‘--exclude=GLOB’ Skip any command-line file with a name suffix that matches the pattern GLOB, using wildcard matching; a name suffix is either the whole name, or any suffix starting after a ‘/’ and before a non-‘/’. When searching recursively, skip any subfile whose base name matches GLOB; the base name is the part after the last ‘/’. A pattern can use ‘*’, ‘?’, and ‘[’...‘]’ as wildcards, and ‘\’ to quote a wildcard or backslash character literally. ‘--exclude-from=FILE’ Skip files whose name matches any of the patterns read from FILE (using wildcard matching as described under ‘--exclude’). ‘--exclude-dir=GLOB’ Skip any command-line directory with a name suffix that matches the pattern GLOB. When searching recursively, skip any subdirectory whose base name matches GLOB. Ignore any redundant trailing slashes in GLOB. ‘-I’ Process a binary file as if it did not contain matching data; this is equivalent to the ‘--binary-files=without-match’ option. ‘--include=GLOB’ Search only files whose name matches GLOB, using wildcard matching as described under ‘--exclude’. ‘-r’ ‘--recursive’ For each directory operand, read and process all files in that directory, recursively. Follow symbolic links on the command line, but skip symlinks that are encountered recursively. Note that if no file operand is given, grep searches the working directory. This is the same as the ‘--directories=recurse’ option. ‘-R’ ‘--dereference-recursive’ For each directory operand, read and process all files in that directory, recursively, following all symbolic links.  File: grep.info-t, Node: Other Options, Prev: File and Directory Selection, Up: Command-line Options 2.1.7 Other Options ------------------- ‘--line-buffered’ Use line buffering on output. This can cause a performance penalty. ‘-U’ ‘--binary’ Treat the file(s) as binary. By default, under MS-DOS and MS-Windows, ‘grep’ guesses whether a file is text or binary as described for the ‘--binary-files’ option. If ‘grep’ decides the file is a text file, it strips carriage returns from the original file contents (to make regular expressions with ‘^’ and ‘$’ work correctly). Specifying ‘-U’ overrules this guesswork, causing all files to be read and passed to the matching mechanism verbatim; if the file is a text file with ‘CR/LF’ pairs at the end of each line, this will cause some regular expressions to fail. This option has no effect on platforms other than MS-DOS and MS-Windows. ‘-z’ ‘--null-data’ Treat input and output data as sequences of lines, each terminated by a zero byte (the ASCII NUL character) instead of a newline. Like the ‘-Z’ or ‘--null’ option, this option can be used with commands like ‘sort -z’ to process arbitrary file names.  File: grep.info-t, Node: Environment Variables, Next: Exit Status, Prev: Command-line Options, Up: Invoking 2.2 Environment Variables ========================= The behavior of ‘grep’ is affected by the following environment variables. The locale for category ‘LC_FOO’ is specified by examining the three environment variables ‘LC_ALL’, ‘LC_FOO’, and ‘LANG’, in that order. The first of these variables that is set specifies the locale. For example, if ‘LC_ALL’ is not set, but ‘LC_COLLATE’ is set to ‘pt_BR’, then the Brazilian Portuguese locale is used for the ‘LC_COLLATE’ category. As a special case for ‘LC_MESSAGES’ only, the environment variable ‘LANGUAGE’ can contain a colon-separated list of languages that overrides the three environment variables that ordinarily specify the ‘LC_MESSAGES’ category. The ‘C’ locale is used if none of these environment variables are set, if the locale catalog is not installed, or if ‘grep’ was not compiled with national language support (NLS). The shell command ‘locale -a’ lists locales that are currently available. Many of the environment variables in the following list let you control highlighting using Select Graphic Rendition (SGR) commands interpreted by the terminal or terminal emulator. (See the section in the documentation of your text terminal for permitted values and their meanings as character attributes.) These substring values are integers in decimal representation and can be concatenated with semicolons. ‘grep’ takes care of assembling the result into a complete SGR sequence (‘\33[’...‘m’). Common values to concatenate include ‘1’ for bold, ‘4’ for underline, ‘5’ for blink, ‘7’ for inverse, ‘39’ for default foreground color, ‘30’ to ‘37’ for foreground colors, ‘90’ to ‘97’ for 16-color mode foreground colors, ‘38;5;0’ to ‘38;5;255’ for 88-color and 256-color modes foreground colors, ‘49’ for default background color, ‘40’ to ‘47’ for background colors, ‘100’ to ‘107’ for 16-color mode background colors, and ‘48;5;0’ to ‘48;5;255’ for 88-color and 256-color modes background colors. The two-letter names used in the ‘GREP_COLORS’ environment variable (and some of the others) refer to terminal “capabilities,” the ability of a terminal to highlight text, or change its color, and so on. These capabilities are stored in an online database and accessed by the ‘terminfo’ library. ‘GREP_OPTIONS’ This variable specifies default options to be placed in front of any explicit options. As this causes problems when writing portable scripts, this feature will be removed in a future release of ‘grep’, and ‘grep’ warns if it is used. Please use an alias or script instead. For example, if ‘grep’ is in the directory ‘/usr/bin’ you can prepend ‘$HOME/bin’ to your ‘PATH’ and create an executable script ‘$HOME/bin/grep’ containing the following: #! /bin/sh export PATH=/usr/bin exec grep --color=auto --devices=skip "$@" ‘GREP_COLOR’ This variable specifies the color used to highlight matched (non-empty) text. It is deprecated in favor of ‘GREP_COLORS’, but still supported. The ‘mt’, ‘ms’, and ‘mc’ capabilities of ‘GREP_COLORS’ have priority over it. It can only specify the color used to highlight the matching non-empty text in any matching line (a selected line when the ‘-v’ command-line option is omitted, or a context line when ‘-v’ is specified). The default is ‘01;31’, which means a bold red foreground text on the terminal’s default background. ‘GREP_COLORS’ This variable specifies the colors and other attributes used to highlight various parts of the output. Its value is a colon-separated list of ‘terminfo’ capabilities that defaults to ‘ms=01;31:mc=01;31:sl=:cx=:fn=35:ln=32:bn=32:se=36’ with the ‘rv’ and ‘ne’ boolean capabilities omitted (i.e., false). Supported capabilities are as follows. ‘sl=’ SGR substring for whole selected lines (i.e., matching lines when the ‘-v’ command-line option is omitted, or non-matching lines when ‘-v’ is specified). If however the boolean ‘rv’ capability and the ‘-v’ command-line option are both specified, it applies to context matching lines instead. The default is empty (i.e., the terminal’s default color pair). ‘cx=’ SGR substring for whole context lines (i.e., non-matching lines when the ‘-v’ command-line option is omitted, or matching lines when ‘-v’ is specified). If however the boolean ‘rv’ capability and the ‘-v’ command-line option are both specified, it applies to selected non-matching lines instead. The default is empty (i.e., the terminal’s default color pair). ‘rv’ Boolean value that reverses (swaps) the meanings of the ‘sl=’ and ‘cx=’ capabilities when the ‘-v’ command-line option is specified. The default is false (i.e., the capability is omitted). ‘mt=01;31’ SGR substring for matching non-empty text in any matching line (i.e., a selected line when the ‘-v’ command-line option is omitted, or a context line when ‘-v’ is specified). Setting this is equivalent to setting both ‘ms=’ and ‘mc=’ at once to the same value. The default is a bold red text foreground over the current line background. ‘ms=01;31’ SGR substring for matching non-empty text in a selected line. (This is used only when the ‘-v’ command-line option is omitted.) The effect of the ‘sl=’ (or ‘cx=’ if ‘rv’) capability remains active when this takes effect. The default is a bold red text foreground over the current line background. ‘mc=01;31’ SGR substring for matching non-empty text in a context line. (This is used only when the ‘-v’ command-line option is specified.) The effect of the ‘cx=’ (or ‘sl=’ if ‘rv’) capability remains active when this takes effect. The default is a bold red text foreground over the current line background. ‘fn=35’ SGR substring for file names prefixing any content line. The default is a magenta text foreground over the terminal’s default background. ‘ln=32’ SGR substring for line numbers prefixing any content line. The default is a green text foreground over the terminal’s default background. ‘bn=32’ SGR substring for byte offsets prefixing any content line. The default is a green text foreground over the terminal’s default background. ‘se=36’ SGR substring for separators that are inserted between selected line fields (‘:’), between context line fields (‘-’), and between groups of adjacent lines when nonzero context is specified (‘--’). The default is a cyan text foreground over the terminal’s default background. ‘ne’ Boolean value that prevents clearing to the end of line using Erase in Line (EL) to Right (‘\33[K’) each time a colorized item ends. This is needed on terminals on which EL is not supported. It is otherwise useful on terminals for which the ‘back_color_erase’ (‘bce’) boolean ‘terminfo’ capability does not apply, when the chosen highlight colors do not affect the background, or when EL is too slow or causes too much flicker. The default is false (i.e., the capability is omitted). Note that boolean capabilities have no ‘=’... part. They are omitted (i.e., false) by default and become true when specified. ‘LC_ALL’ ‘LC_COLLATE’ ‘LANG’ These variables specify the locale for the ‘LC_COLLATE’ category, which might affect how range expressions like ‘[a-z]’ are interpreted. ‘LC_ALL’ ‘LC_CTYPE’ ‘LANG’ These variables specify the locale for the ‘LC_CTYPE’ category, which determines the type of characters, e.g., which characters are whitespace. This category also determines the character encoding, that is, whether text is encoded in UTF-8, ASCII, or some other encoding. In the ‘C’ or ‘POSIX’ locale, all characters are encoded as a single byte and every byte is a valid character. ‘LANGUAGE’ ‘LC_ALL’ ‘LC_MESSAGES’ ‘LANG’ These variables specify the locale for the ‘LC_MESSAGES’ category, which determines the language that ‘grep’ uses for messages. The default ‘C’ locale uses American English messages. ‘POSIXLY_CORRECT’ If set, ‘grep’ behaves as POSIX requires; otherwise, ‘grep’ behaves more like other GNU programs. POSIX requires that options that follow file names must be treated as file names; by default, such options are permuted to the front of the operand list and are treated as options. Also, ‘POSIXLY_CORRECT’ disables special handling of an invalid bracket expression. *Note invalid-bracket-expr::. ‘_N_GNU_nonoption_argv_flags_’ (Here ‘N’ is ‘grep’’s numeric process ID.) If the Ith character of this environment variable’s value is ‘1’, do not consider the Ith operand of ‘grep’ to be an option, even if it appears to be one. A shell can put this variable in the environment for each command it runs, specifying which operands are the results of file name wildcard expansion and therefore should not be treated as options. This behavior is available only with the GNU C library, and only when ‘POSIXLY_CORRECT’ is not set.  File: grep.info-t, Node: Exit Status, Next: grep Programs, Prev: Environment Variables, Up: Invoking 2.3 Exit Status =============== Normally the exit status is 0 if a line is selected, 1 if no lines were selected, and 2 if an error occurred. However, if the ‘-q’ or ‘--quiet’ or ‘--silent’ option is used and a line is selected, the exit status is 0 even if an error occurred. Other ‘grep’ implementations may exit with status greater than 2 on error.  File: grep.info-t, Node: grep Programs, Prev: Exit Status, Up: Invoking 2.4 ‘grep’ Programs =================== ‘grep’ searches the named input files for lines containing a match to the given pattern. By default, ‘grep’ prints the matching lines. A file named ‘-’ stands for standard input. If no input is specified, ‘grep’ searches the working directory ‘.’ if given a command-line option specifying recursion; otherwise, ‘grep’ searches standard input. There are four major variants of ‘grep’, controlled by the following options. ‘-G’ ‘--basic-regexp’ Interpret the pattern as a basic regular expression (BRE). This is the default. ‘-E’ ‘--extended-regexp’ Interpret the pattern as an extended regular expression (ERE). (‘-E’ is specified by POSIX.) ‘-F’ ‘--fixed-strings’ Interpret the pattern as a list of fixed strings (instead of regular expressions), separated by newlines, any of which is to be matched. (‘-F’ is specified by POSIX.) ‘-P’ ‘--perl-regexp’ Interpret the pattern as a Perl-compatible regular expression (PCRE). This is highly experimental and ‘grep -P’ may warn of unimplemented features. In addition, two variant programs ‘egrep’ and ‘fgrep’ are available. ‘egrep’ is the same as ‘grep -E’. ‘fgrep’ is the same as ‘grep -F’. Direct invocation as either ‘egrep’ or ‘fgrep’ is deprecated, but is provided to allow historical applications that rely on them to run unmodified.  File: grep.info-t, Node: Regular Expressions, Next: Usage, Prev: Invoking, Up: Top 3 Regular Expressions ********************* A “regular expression” is a pattern that describes a set of strings. Regular expressions are constructed analogously to arithmetic expressions, by using various operators to combine smaller expressions. ‘grep’ understands three different versions of regular expression syntax: “basic” (BRE), “extended” (ERE) and “perl” (PCRE). In GNU ‘grep’, there is no difference in available functionality between the basic and extended syntaxes. In other implementations, basic regular expressions are less powerful. The following description applies to extended regular expressions; differences for basic regular expressions are summarized afterwards. Perl-compatible regular expressions give additional functionality, and are documented in the pcresyntax(3) and pcrepattern(3) manual pages, but work only if PCRE is available in the system. * Menu: * Fundamental Structure:: * Character Classes and Bracket Expressions:: * The Backslash Character and Special Expressions:: * Anchoring:: * Back-references and Subexpressions:: * Basic vs Extended::  File: grep.info-t, Node: Fundamental Structure, Next: Character Classes and Bracket Expressions, Up: Regular Expressions 3.1 Fundamental Structure ========================= The fundamental building blocks are the regular expressions that match a single character. Most characters, including all letters and digits, are regular expressions that match themselves. Any meta-character with special meaning may be quoted by preceding it with a backslash. A regular expression may be followed by one of several repetition operators: ‘.’ The period ‘.’ matches any single character. ‘?’ The preceding item is optional and will be matched at most once. ‘*’ The preceding item will be matched zero or more times. ‘+’ The preceding item will be matched one or more times. ‘{N}’ The preceding item is matched exactly N times. ‘{N,}’ The preceding item is matched N or more times. ‘{,M}’ The preceding item is matched at most M times. This is a GNU extension. ‘{N,M}’ The preceding item is matched at least N times, but not more than M times. The empty regular expression matches the empty string. Two regular expressions may be concatenated; the resulting regular expression matches any string formed by concatenating two substrings that respectively match the concatenated expressions. Two regular expressions may be joined by the infix operator ‘|’; the resulting regular expression matches any string matching either alternate expression. Repetition takes precedence over concatenation, which in turn takes precedence over alternation. A whole expression may be enclosed in parentheses to override these precedence rules and form a subexpression. An unmatched ‘)’ matches just itself.  File: grep.info-t, Node: Character Classes and Bracket Expressions, Next: The Backslash Character and Special Expressions, Prev: Fundamental Structure, Up: Regular Expressions 3.2 Character Classes and Bracket Expressions ============================================= A “bracket expression” is a list of characters enclosed by ‘[’ and ‘]’. It matches any single character in that list; if the first character of the list is the caret ‘^’, then it matches any character *not* in the list. For example, the regular expression ‘[0123456789]’ matches any single digit. Within a bracket expression, a “range expression” consists of two characters separated by a hyphen. It matches any single character that sorts between the two characters, inclusive. In the default C locale, the sorting sequence is the native character order; for example, ‘[a-d]’ is equivalent to ‘[abcd]’. In other locales, the sorting sequence is not specified, and ‘[a-d]’ might be equivalent to ‘[abcd]’ or to ‘[aBbCcDd]’, or it might fail to match any character, or the set of characters that it matches might even be erratic. To obtain the traditional interpretation of bracket expressions, you can use the ‘C’ locale by setting the ‘LC_ALL’ environment variable to the value ‘C’. Finally, certain named classes of characters are predefined within bracket expressions, as follows. Their interpretation depends on the ‘LC_CTYPE’ locale; for example, ‘[[:alnum:]]’ means the character class of numbers and letters in the current locale. ‘[:alnum:]’ Alphanumeric characters: ‘[:alpha:]’ and ‘[:digit:]’; in the ‘C’ locale and ASCII character encoding, this is the same as ‘[0-9A-Za-z]’. ‘[:alpha:]’ Alphabetic characters: ‘[:lower:]’ and ‘[:upper:]’; in the ‘C’ locale and ASCII character encoding, this is the same as ‘[A-Za-z]’. ‘[:blank:]’ Blank characters: space and tab. ‘[:cntrl:]’ Control characters. In ASCII, these characters have octal codes 000 through 037, and 177 (DEL). In other character sets, these are the equivalent characters, if any. ‘[:digit:]’ Digits: ‘0 1 2 3 4 5 6 7 8 9’. ‘[:graph:]’ Graphical characters: ‘[:alnum:]’ and ‘[:punct:]’. ‘[:lower:]’ Lower-case letters; in the ‘C’ locale and ASCII character encoding, this is ‘a b c d e f g h i j k l m n o p q r s t u v w x y z’. ‘[:print:]’ Printable characters: ‘[:alnum:]’, ‘[:punct:]’, and space. ‘[:punct:]’ Punctuation characters; in the ‘C’ locale and ASCII character encoding, this is ‘! " # $ % & ' ( ) * + , - . / : ; < = > ? @ [ \ ] ^ _ ` { | } ~’. ‘[:space:]’ Space characters: in the ‘C’ locale, this is tab, newline, vertical tab, form feed, carriage return, and space. *Note Usage::, for more discussion of matching newlines. ‘[:upper:]’ Upper-case letters: in the ‘C’ locale and ASCII character encoding, this is ‘A B C D E F G H I J K L M N O P Q R S T U V W X Y Z’. ‘[:xdigit:]’ Hexadecimal digits: ‘0 1 2 3 4 5 6 7 8 9 A B C D E F a b c d e f’. Note that the brackets in these class names are part of the symbolic names, and must be included in addition to the brackets delimiting the bracket expression. If you mistakenly omit the outer brackets, and search for say, ‘[:upper:]’, GNU ‘grep’ prints a diagnostic and exits with status 2, on the assumption that you did not intend to search for the nominally equivalent regular expression: ‘[:epru]’. Set the ‘POSIXLY_CORRECT’ environment variable to disable this feature. Most meta-characters lose their special meaning inside bracket expressions. ‘]’ ends the bracket expression if it’s not the first list item. So, if you want to make the ‘]’ character a list item, you must put it first. ‘[.’ represents the open collating symbol. ‘.]’ represents the close collating symbol. ‘[=’ represents the open equivalence class. ‘=]’ represents the close equivalence class. ‘[:’ represents the open character class symbol, and should be followed by a valid character class name. ‘:]’ represents the close character class symbol. ‘-’ represents the range if it’s not first or last in a list or the ending point of a range. ‘^’ represents the characters not in the list. If you want to make the ‘^’ character a list item, place it anywhere but first.  File: grep.info-t, Node: The Backslash Character and Special Expressions, Next: Anchoring, Prev: Character Classes and Bracket Expressions, Up: Regular Expressions 3.3 The Backslash Character and Special Expressions =================================================== The ‘\’ character, when followed by certain ordinary characters, takes a special meaning: ‘\b’ Match the empty string at the edge of a word. ‘\B’ Match the empty string provided it’s not at the edge of a word. ‘\<’ Match the empty string at the beginning of word. ‘\>’ Match the empty string at the end of word. ‘\w’ Match word constituent, it is a synonym for ‘[_[:alnum:]]’. ‘\W’ Match non-word constituent, it is a synonym for ‘[^_[:alnum:]]’. ‘\s’ Match whitespace, it is a synonym for ‘[[:space:]]’. ‘\S’ Match non-whitespace, it is a synonym for ‘[^[:space:]]’. For example, ‘\brat\b’ matches the separate word ‘rat’, ‘\Brat\B’ matches ‘crate’ but not ‘furry rat’.  File: grep.info-t, Node: Anchoring, Next: Back-references and Subexpressions, Prev: The Backslash Character and Special Expressions, Up: Regular Expressions 3.4 Anchoring ============= The caret ‘^’ and the dollar sign ‘$’ are meta-characters that respectively match the empty string at the beginning and end of a line. They are termed “anchors”, since they force the match to be “anchored” to beginning or end of a line, respectively.  File: grep.info-t, Node: Back-references and Subexpressions, Next: Basic vs Extended, Prev: Anchoring, Up: Regular Expressions 3.5 Back-references and Subexpressions ====================================== The back-reference ‘\N’, where N is a single digit, matches the substring previously matched by the Nth parenthesized subexpression of the regular expression. For example, ‘(a)\1’ matches ‘aa’. When used with alternation, if the group does not participate in the match then the back-reference makes the whole match fail. For example, ‘a(.)|b\1’ will not match ‘ba’. When multiple regular expressions are given with ‘-e’ or from a file (‘-f FILE’), back-references are local to each expression.  File: grep.info-t, Node: Basic vs Extended, Prev: Back-references and Subexpressions, Up: Regular Expressions 3.6 Basic vs Extended Regular Expressions ========================================= In basic regular expressions the meta-characters ‘?’, ‘+’, ‘{’, ‘|’, ‘(’, and ‘)’ lose their special meaning; instead use the backslashed versions ‘\?’, ‘\+’, ‘\{’, ‘\|’, ‘\(’, and ‘\)’. Traditional ‘egrep’ did not support the ‘{’ meta-character, and some ‘egrep’ implementations support ‘\{’ instead, so portable scripts should avoid ‘{’ in ‘grep -E’ patterns and should use ‘[{]’ to match a literal ‘{’. GNU ‘grep -E’ attempts to support traditional usage by assuming that ‘{’ is not special if it would be the start of an invalid interval specification. For example, the command ‘grep -E '{1'’ searches for the two-character string ‘{1’ instead of reporting a syntax error in the regular expression. POSIX allows this behavior as an extension, but portable scripts should avoid it.  File: grep.info-t, Node: Usage, Next: Reporting Bugs, Prev: Regular Expressions, Up: Top 4 Usage ******* Here is an example command that invokes GNU ‘grep’: grep -i 'hello.*world' menu.h main.c This lists all lines in the files ‘menu.h’ and ‘main.c’ that contain the string ‘hello’ followed by the string ‘world’; this is because ‘.*’ matches zero or more characters within a line. *Note Regular Expressions::. The ‘-i’ option causes ‘grep’ to ignore case, causing it to match the line ‘Hello, world!’, which it would not otherwise match. *Note Invoking::, for more details about how to invoke ‘grep’. Here are some common questions and answers about ‘grep’ usage. 1. How can I list just the names of matching files? grep -l 'main' *.c lists the names of all C files in the current directory whose contents mention ‘main’. 2. How do I search directories recursively? grep -r 'hello' /home/gigi searches for ‘hello’ in all files under the ‘/home/gigi’ directory. For more control over which files are searched, use ‘find’, ‘grep’, and ‘xargs’. For example, the following command searches only C files: find /home/gigi -name '*.c' -print0 | xargs -0r grep -H 'hello' This differs from the command: grep -H 'hello' *.c which merely looks for ‘hello’ in all files in the current directory whose names end in ‘.c’. The ‘find ...’ command line above is more similar to the command: grep -rH --include='*.c' 'hello' /home/gigi 3. What if a pattern has a leading ‘-’? grep -e '--cut here--' * searches for all lines matching ‘--cut here--’. Without ‘-e’, ‘grep’ would attempt to parse ‘--cut here--’ as a list of options. 4. Suppose I want to search for a whole word, not a part of a word? grep -w 'hello' * searches only for instances of ‘hello’ that are entire words; it does not match ‘Othello’. For more control, use ‘\<’ and ‘\>’ to match the start and end of words. For example: grep 'hello\>' * searches only for words ending in ‘hello’, so it matches the word ‘Othello’. 5. How do I output context around the matching lines? grep -C 2 'hello' * prints two lines of context around each matching line. 6. How do I force ‘grep’ to print the name of the file? Append ‘/dev/null’: grep 'eli' /etc/passwd /dev/null gets you: /etc/passwd:eli:x:2098:1000:Eli Smith:/home/eli:/bin/bash Alternatively, use ‘-H’, which is a GNU extension: grep -H 'eli' /etc/passwd 7. Why do people use strange regular expressions on ‘ps’ output? ps -ef | grep '[c]ron' If the pattern had been written without the square brackets, it would have matched not only the ‘ps’ output line for ‘cron’, but also the ‘ps’ output line for ‘grep’. Note that on some platforms, ‘ps’ limits the output to the width of the screen; ‘grep’ does not have any limit on the length of a line except the available memory. 8. Why does ‘grep’ report “Binary file matches”? If ‘grep’ listed all matching “lines” from a binary file, it would probably generate output that is not useful, and it might even muck up your display. So GNU ‘grep’ suppresses output from files that appear to be binary files. To force GNU ‘grep’ to output lines even from files that appear to be binary, use the ‘-a’ or ‘--binary-files=text’ option. To eliminate the “Binary file matches” messages, use the ‘-I’ or ‘--binary-files=without-match’ option. 9. Why doesn’t ‘grep -lv’ print non-matching file names? ‘grep -lv’ lists the names of all files containing one or more lines that do not match. To list the names of all files that contain no matching lines, use the ‘-L’ or ‘--files-without-match’ option. 10. I can do “OR” with ‘|’, but what about “AND”? grep 'paul' /etc/motd | grep 'franc,ois' finds all lines that contain both ‘paul’ and ‘franc,ois’. 11. Why does the empty pattern match every input line? The ‘grep’ command searches for lines that contain strings that match a pattern. Every line contains the empty string, so an empty pattern causes ‘grep’ to find a match on each line. It is not the only such pattern: ‘^’, ‘$’, ‘.*’, and many other patterns cause ‘grep’ to match every line. To match empty lines, use the pattern ‘^$’. To match blank lines, use the pattern ‘^[[:blank:]]*$’. To match no lines at all, use the command ‘grep -f /dev/null’. 12. How can I search in both standard input and in files? Use the special file name ‘-’: cat /etc/passwd | grep 'alain' - /etc/motd 13. How to express palindromes in a regular expression? It can be done by using back-references; for example, a palindrome of 4 characters can be written with a BRE: grep -w -e '\(.\)\(.\).\2\1' file It matches the word “radar” or “civic.” Guglielmo Bondioni proposed a single RE that finds all palindromes up to 19 characters long using 9 subexpressions and 9 back-references: grep -E -e '^(.?)(.?)(.?)(.?)(.?)(.?)(.?)(.?)(.?).?\9\8\7\6\5\4\3\2\1$' file Note this is done by using GNU ERE extensions; it might not be portable to other implementations of ‘grep’. 14. Why is this back-reference failing? echo 'ba' | grep -E '(a)\1|b\1' This gives no output, because the first alternate ‘(a)\1’ does not match, as there is no ‘aa’ in the input, so the ‘\1’ in the second alternate has nothing to refer back to, meaning it will never match anything. (The second alternate in this example can only match if the first alternate has matched—making the second one superfluous.) 15. How can I match across lines? Standard grep cannot do this, as it is fundamentally line-based. Therefore, merely using the ‘[:space:]’ character class does not match newlines in the way you might expect. With the GNU ‘grep’ option ‘-z’ (‘--null-data’), each input “line” is terminated by a null byte; *note Other Options::. Thus, you can match newlines in the input, but typically if there is a match the entire input is output, so this usage is often combined with output-suppressing options like ‘-q’, e.g.: printf 'foo\nbar\n' | grep -z -q 'foo[[:space:]]\+bar' If this does not suffice, you can transform the input before giving it to ‘grep’, or turn to ‘awk’, ‘sed’, ‘perl’, or many other utilities that are designed to operate across lines. 16. What do ‘grep’, ‘fgrep’, and ‘egrep’ stand for? The name ‘grep’ comes from the way line editing was done on Unix. For example, ‘ed’ uses the following syntax to print a list of matching lines on the screen: global/regular expression/print g/re/p ‘fgrep’ stands for Fixed ‘grep’; ‘egrep’ stands for Extended ‘grep’.  File: grep.info-t, Node: Reporting Bugs, Next: Copying, Prev: Usage, Up: Top 5 Reporting bugs **************** Bug reports can be found at the GNU bug report logs for ‘grep’ (http://debbugs.gnu.org/cgi/pkgreport.cgi?package=grep). If you find a bug not listed there, please email it to to create a new bug report. 5.1 Known Bugs ============== Large repetition counts in the ‘{n,m}’ construct may cause ‘grep’ to use lots of memory. In addition, certain other obscure regular expressions require exponential time and space, and may cause ‘grep’ to run out of memory. Back-references are very slow, and may require exponential time.  File: grep.info-t, Node: Copying, Next: Index, Prev: Reporting Bugs, Up: Top 6 Copying ********* GNU ‘grep’ is licensed under the GNU GPL, which makes it “free software”. The “free” in “free software” refers to liberty, not price. As some GNU project advocates like to point out, think of “free speech” rather than “free beer”. In short, you have the right (freedom) to run and change ‘grep’ and distribute it to other people, and—if you want—charge money for doing either. The important restriction is that you have to grant your recipients the same rights and impose the same restrictions. This general method of licensing software is sometimes called “open source”. The GNU project prefers the term “free software” for reasons outlined at . This manual is free documentation in the same sense. The documentation license is included below. The license for the program is available with the source code, or at . * Menu: * GNU Free Documentation License::  File: grep.info-t, Node: GNU Free Documentation License, Up: Copying 6.1 GNU Free Documentation License ================================== Version 1.3, 3 November 2008 Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc. Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. 0. PREAMBLE The purpose of this License is to make a manual, textbook, or other functional and useful document “free” in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others. 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The operator of an MMC Site may republish an MMC contained in the site under CC-BY-SA on the same site at any time before August 1, 2009, provided the MMC is eligible for relicensing. ADDENDUM: How to use this License for your documents ==================================================== To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page: Copyright (C) YEAR YOUR NAME. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled ``GNU Free Documentation License''. If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the “with…Texts.” line with this: with the Invariant Sections being LIST THEIR TITLES, with the Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST. If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation. If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.  File: grep.info-t, Node: Index, Prev: Copying, Up: Top Index ***** [index] * Menu: * *: Fundamental Structure. (line 21) * +: Fundamental Structure. (line 24) * --after-context: Context Line Control. (line 13) * --basic-regexp: grep Programs. (line 15) * --before-context: Context Line Control. (line 17) * --binary: Other Options. (line 12) * --binary-files: File and Directory Selection. (line 12) * --byte-offset: Output Line Prefix Control. (line 12) * --color: General Output Control. (line 14) * --colour: General Output Control. (line 14) * --context: Context Line Control. (line 22) * --count: General Output Control. (line 8) * --dereference-recursive: File and Directory Selection. (line 108) * --devices: File and Directory Selection. (line 50) * --directories: File and Directory Selection. (line 61) * --exclude: File and Directory Selection. (line 72) * --exclude-dir: File and Directory Selection. (line 85) * --exclude-from: File and Directory Selection. (line 81) * --extended-regexp: grep Programs. (line 20) * --file: Matching Control. (line 14) * --files-with-matches: General Output Control. (line 35) * --files-without-match: General Output Control. (line 29) * --fixed-strings: grep Programs. (line 25) * --group-separator: Context Line Control. (line 25) * --group-separator <1>: Context Line Control. (line 29) * --help: Generic Program Information. (line 7) * --ignore-case: Matching Control. (line 23) * --include: File and Directory Selection. (line 95) * --initial-tab: Output Line Prefix Control. (line 43) * --invert-match: Matching Control. (line 42) * --label: Output Line Prefix Control. (line 30) * --line-buffered: Other Options. (line 7) * --line-number: Output Line Prefix Control. (line 38) * --line-regexp: Matching Control. (line 57) * --max-count: General Output Control. (line 42) * --no-filename: Output Line Prefix Control. (line 25) * --no-messages: General Output Control. (line 87) * --null: Output Line Prefix Control. (line 63) * --null-data: Other Options. (line 25) * --only-matching: General Output Control. (line 74) * --perl-regexp: grep Programs. (line 31) * --quiet: General Output Control. (line 80) * --recursive: File and Directory Selection. (line 100) * --regexp=PATTERN: Matching Control. (line 8) * --silent: General Output Control. (line 80) * --text: File and Directory Selection. (line 8) * --unix-byte-offsets: Output Line Prefix Control. (line 53) * --version: Generic Program Information. (line 12) * --with-filename: Output Line Prefix Control. (line 20) * --word-regexp: Matching Control. (line 47) * -A: Context Line Control. (line 13) * -a: File and Directory Selection. (line 8) * -b: Output Line Prefix Control. (line 12) * -B: Context Line Control. (line 17) * -c: General Output Control. (line 8) * -C: Context Line Control. (line 22) * -D: File and Directory Selection. (line 50) * -d: File and Directory Selection. (line 61) * -e: Matching Control. (line 8) * -E: grep Programs. (line 20) * -f: Matching Control. (line 14) * -F: grep Programs. (line 25) * -G: grep Programs. (line 15) * -H: Output Line Prefix Control. (line 20) * -h: Output Line Prefix Control. (line 25) * -i: Matching Control. (line 23) * -L: General Output Control. (line 29) * -l: General Output Control. (line 35) * -m: General Output Control. (line 42) * -n: Output Line Prefix Control. (line 38) * -NUM: Context Line Control. (line 22) * -o: General Output Control. (line 74) * -P: grep Programs. (line 31) * -q: General Output Control. (line 80) * -r: File and Directory Selection. (line 100) * -R: File and Directory Selection. (line 108) * -s: General Output Control. (line 87) * -T: Output Line Prefix Control. (line 43) * -u: Output Line Prefix Control. (line 53) * -U: Other Options. (line 12) * -V: Generic Program Information. (line 12) * -v: Matching Control. (line 42) * -w: Matching Control. (line 47) * -x: Matching Control. (line 57) * -y: Matching Control. (line 23) * -Z: Output Line Prefix Control. (line 63) * -z: Other Options. (line 25) * .: Fundamental Structure. (line 15) * ?: Fundamental Structure. (line 18) * _N_GNU_nonoption_argv_flags_ environment variable: Environment Variables. (line 193) * {,M}: Fundamental Structure. (line 33) * {N,M}: Fundamental Structure. (line 37) * {N,}: Fundamental Structure. (line 30) * {N}: Fundamental Structure. (line 27) * after context: Context Line Control. (line 13) * alnum character class: Character Classes and Bracket Expressions. (line 29) * alpha character class: Character Classes and Bracket Expressions. (line 34) * alphabetic characters: Character Classes and Bracket Expressions. (line 34) * alphanumeric characters: Character Classes and Bracket Expressions. (line 29) * anchoring: Anchoring. (line 6) * asterisk: Fundamental Structure. (line 21) * back-reference: Back-references and Subexpressions. (line 6) * backslash: The Backslash Character and Special Expressions. (line 6) * basic regular expressions: Basic vs Extended. (line 6) * before context: Context Line Control. (line 17) * binary files: File and Directory Selection. (line 8) * binary files <1>: File and Directory Selection. (line 12) * binary files, MS-DOS/MS-Windows: Other Options. (line 12) * blank character class: Character Classes and Bracket Expressions. (line 39) * blank characters: Character Classes and Bracket Expressions. (line 39) * bn GREP_COLORS capability: Environment Variables. (line 134) * braces, first argument omitted: Fundamental Structure. (line 33) * braces, one argument: Fundamental Structure. (line 27) * braces, second argument omitted: Fundamental Structure. (line 30) * braces, two arguments: Fundamental Structure. (line 37) * bracket expression: Character Classes and Bracket Expressions. (line 6) * Bugs, known: Reporting Bugs. (line 14) * bugs, reporting: Reporting Bugs. (line 6) * byte offset: Output Line Prefix Control. (line 12) * byte offsets, on MS-DOS/MS-Windows: Output Line Prefix Control. (line 53) * case insensitive search: Matching Control. (line 23) * changing name of standard input: Output Line Prefix Control. (line 30) * character class: Character Classes and Bracket Expressions. (line 6) * character classes: Character Classes and Bracket Expressions. (line 28) * character type: Environment Variables. (line 161) * classes of characters: Character Classes and Bracket Expressions. (line 28) * cntrl character class: Character Classes and Bracket Expressions. (line 42) * context: Context Line Control. (line 22) * context lines, after match: Context Line Control. (line 13) * context lines, before match: Context Line Control. (line 17) * control characters: Character Classes and Bracket Expressions. (line 42) * copying: Copying. (line 6) * counting lines: General Output Control. (line 8) * cx GREP_COLORS capability: Environment Variables. (line 85) * default options environment variable: Environment Variables. (line 45) * device search: File and Directory Selection. (line 50) * digit character class: Character Classes and Bracket Expressions. (line 47) * digit characters: Character Classes and Bracket Expressions. (line 47) * directory search: File and Directory Selection. (line 61) * dot: Fundamental Structure. (line 15) * environment variables: Environment Variables. (line 44) * exclude directories: File and Directory Selection. (line 85) * exclude files: File and Directory Selection. (line 72) * exclude files <1>: File and Directory Selection. (line 81) * exit status: Exit Status. (line 6) * FAQ about ‘grep’ usage: Usage. (line 17) * files which don’t match: General Output Control. (line 29) * fn GREP_COLORS capability: Environment Variables. (line 124) * fn GREP_COLORS capability <1>: Environment Variables. (line 139) * graph character class: Character Classes and Bracket Expressions. (line 50) * graphic characters: Character Classes and Bracket Expressions. (line 50) * ‘grep’ programs: grep Programs. (line 6) * GREP_COLOR environment variable: Environment Variables. (line 58) * GREP_COLORS environment variable: Environment Variables. (line 69) * GREP_OPTIONS environment variable: Environment Variables. (line 45) * group separator: Context Line Control. (line 25) * group separator <1>: Context Line Control. (line 29) * hexadecimal digits: Character Classes and Bracket Expressions. (line 74) * highlight markers: Environment Variables. (line 58) * highlight markers <1>: Environment Variables. (line 69) * highlight, color, colour: General Output Control. (line 14) * include files: File and Directory Selection. (line 95) * interval specifications: Basic vs Extended. (line 10) * invert matching: Matching Control. (line 42) * LANG environment variable: Environment Variables. (line 9) * LANG environment variable <1>: Environment Variables. (line 161) * LANG environment variable <2>: Environment Variables. (line 168) * LANG environment variable <3>: Environment Variables. (line 179) * LANGUAGE environment variable: Environment Variables. (line 9) * LANGUAGE environment variable <1>: Environment Variables. (line 179) * language of messages: Environment Variables. (line 179) * LC_ALL environment variable: Environment Variables. (line 9) * LC_ALL environment variable <1>: Environment Variables. (line 161) * LC_ALL environment variable <2>: Environment Variables. (line 168) * LC_ALL environment variable <3>: Environment Variables. (line 179) * LC_COLLATE environment variable: Environment Variables. (line 161) * LC_CTYPE environment variable: Environment Variables. (line 168) * LC_MESSAGES environment variable: Environment Variables. (line 9) * LC_MESSAGES environment variable <1>: Environment Variables. (line 179) * line buffering: Other Options. (line 7) * line numbering: Output Line Prefix Control. (line 38) * ln GREP_COLORS capability: Environment Variables. (line 129) * lower character class: Character Classes and Bracket Expressions. (line 53) * lower-case letters: Character Classes and Bracket Expressions. (line 53) * match expression at most M times: Fundamental Structure. (line 33) * match expression at most once: Fundamental Structure. (line 18) * match expression from N to M times: Fundamental Structure. (line 37) * match expression N or more times: Fundamental Structure. (line 30) * match expression N times: Fundamental Structure. (line 27) * match expression one or more times: Fundamental Structure. (line 24) * match expression zero or more times: Fundamental Structure. (line 21) * match the whole line: Matching Control. (line 57) * matching basic regular expressions: grep Programs. (line 15) * matching extended regular expressions: grep Programs. (line 20) * matching fixed strings: grep Programs. (line 25) * matching Perl-compatible regular expressions: grep Programs. (line 31) * matching whole words: Matching Control. (line 47) * max-count: General Output Control. (line 42) * mc GREP_COLORS capability: Environment Variables. (line 116) * message language: Environment Variables. (line 179) * ms GREP_COLORS capability: Environment Variables. (line 108) * MS-DOS/MS-Windows binary files: Other Options. (line 12) * MS-DOS/MS-Windows byte offsets: Output Line Prefix Control. (line 53) * mt GREP_COLORS capability: Environment Variables. (line 100) * names of matching files: General Output Control. (line 35) * national language support: Environment Variables. (line 161) * national language support <1>: Environment Variables. (line 179) * ne GREP_COLORS capability: Environment Variables. (line 146) * NLS: Environment Variables. (line 161) * no filename prefix: Output Line Prefix Control. (line 25) * numeric characters: Character Classes and Bracket Expressions. (line 47) * only matching: General Output Control. (line 74) * palindromes: Usage. (line 139) * pattern from file: Matching Control. (line 14) * pattern list: Matching Control. (line 8) * period: Fundamental Structure. (line 15) * plus sign: Fundamental Structure. (line 24) * POSIXLY_CORRECT environment variable: Environment Variables. (line 184) * print character class: Character Classes and Bracket Expressions. (line 57) * print non-matching lines: Matching Control. (line 42) * printable characters: Character Classes and Bracket Expressions. (line 57) * punct character class: Character Classes and Bracket Expressions. (line 60) * punctuation characters: Character Classes and Bracket Expressions. (line 60) * question mark: Fundamental Structure. (line 18) * quiet, silent: General Output Control. (line 80) * range expression: Character Classes and Bracket Expressions. (line 12) * recursive search: File and Directory Selection. (line 100) * recursive search <1>: File and Directory Selection. (line 108) * regular expressions: Regular Expressions. (line 6) * return status: Exit Status. (line 6) * rv GREP_COLORS capability: Environment Variables. (line 94) * searching directory trees: File and Directory Selection. (line 72) * searching directory trees <1>: File and Directory Selection. (line 81) * searching directory trees <2>: File and Directory Selection. (line 95) * searching directory trees <3>: File and Directory Selection. (line 100) * searching directory trees <4>: File and Directory Selection. (line 108) * searching for a pattern: Introduction. (line 6) * sl GREP_COLORS capability: Environment Variables. (line 77) * space character class: Character Classes and Bracket Expressions. (line 65) * space characters: Character Classes and Bracket Expressions. (line 65) * subexpression: Back-references and Subexpressions. (line 6) * suppress binary data: File and Directory Selection. (line 8) * suppress error messages: General Output Control. (line 87) * symbolic links: File and Directory Selection. (line 61) * symbolic links <1>: File and Directory Selection. (line 100) * symbolic links <2>: File and Directory Selection. (line 108) * tab-aligned content lines: Output Line Prefix Control. (line 43) * translation of message language: Environment Variables. (line 179) * upper character class: Character Classes and Bracket Expressions. (line 70) * upper-case letters: Character Classes and Bracket Expressions. (line 70) * usage summary, printing: Generic Program Information. (line 7) * usage, examples: Usage. (line 6) * using ‘grep’, Q&A: Usage. (line 17) * variants of ‘grep’: grep Programs. (line 6) * version, printing: Generic Program Information. (line 12) * whitespace characters: Character Classes and Bracket Expressions. (line 65) * with filename prefix: Output Line Prefix Control. (line 20) * xdigit character class: Character Classes and Bracket Expressions. (line 74) * xdigit class: Character Classes and Bracket Expressions. (line 74) * zero-terminated file names: Output Line Prefix Control. (line 63) * zero-terminated lines: Other Options. (line 25)  Tag Table: Node: Top771 Node: Introduction1899 Node: Invoking2641 Node: Command-line Options3414 Node: Generic Program Information4299 Node: Matching Control4775 Node: General Output Control7498 Ref: General Output Control-Footnote-111629 Node: Output Line Prefix Control11698 Node: Context Line Control14760 Node: File and Directory Selection16691 Node: Other Options22133 Node: Environment Variables23441 Node: Exit Status33720 Node: grep Programs34200 Node: Regular Expressions35777 Node: Fundamental Structure36980 Node: Character Classes and Bracket Expressions38788 Ref: invalid-bracket-expr42210 Node: The Backslash Character and Special Expressions43450 Node: Anchoring44524 Node: Back-references and Subexpressions44985 Node: Basic vs Extended45725 Node: Usage46818 Node: Reporting Bugs54298 Node: Copying54982 Node: GNU Free Documentation License56110 Node: Index81415  End Tag Table  Local Variables: coding: utf-8 End: